1. Field of the Invention
The present invention relates to a moving table unit in which a table is attached to a rectilinear motion guide device on each of both side legs of a substantially U-shaped bed thereby relatively rectilinearly moving the table and bed. More particularly, the invention relates to a moving table unit which can freely set the moving velocity and movement amount of the table.
2. Description of the Prior Art
According to a conventional moving table unit, for example, ball screw grooves having different pitches are formed on a single shaft, nuts for ball screws corresponding to the ball screw grooves are fitted therein, one of the nuts is rotatably fixed to a table, the other nut is rotatably fixed to a bed, these nuts are simultaneously or independently rotated, and thereby feeding the table and bed finely or at a high speed due to the difference between the screw pitches or the like. In this case, however, since apparatuses (e.g., a gear, a motor, etc.) to drive the nut of the ball screw are separately attached, the size of the moving table itself is large and the number of parts is also large. Thus, the conventional moving table unit is expensive.
In addition, since the driving force of the motor is indirectly propagated by gear, belt drive, or the like, a backlash occurs and the accurate positioning cannot be performed.